Musnad Abu Ya'la al-Mawsili 7:12

Abu Khaythama narrated to us, Ismail bin Ibrahim narrated to us, from Abd al-Rahman bin Ishaq, from al-Zuhri, from Muhammad bin Jubayr bin Mut'im, from his father, from Abd al-Rahman bin Awf, who said: The Messenger of Allah (may Allah bless him and grant him peace) said: "I witnessed [the pact] with my paternal uncles," and he mentioned the like of it.